1. Field of the Invention
Embodiments of the present general inventive concept relate to a sheet processing device having an improved safety unit to prevent a user accident.
2. Description of the Related Art
Image forming apparatuses are devised to print an image on a printing medium. Examples of image forming apparatuses include printers, copiers, facsimiles, and so-called multifunctional apparatuses that combine some of the functionalities of the aforementioned.
A sheet processing device is provided in a variety of electronic appliances including an image forming apparatus, etc. The sheet processing device performs, e.g., a punching process to punch a hole in a sheet of paper fed thereto, or a stapling process to staple a bundle of sheets of paper.
A sheet of paper discharged from the image forming apparatus is subjected to post treatment while passing through the sheet processing device. The sheet of paper discharged from the image forming apparatus may pass through the sheet processing device in an automatic manner, or in a manual manner.
The sheet processing device may be operated to remove impurities accumulated therein, or to replace consumable elements. Such a removal or replacement operation is performed by a user (or worker) in an open state of the sheet processing device. However, if malfunction of, e.g., a sensor occurs during the operation, implementation of the punching process or stapling process may be impossible and user safety may not be assured.